Re: [Lsr] LSR Working Group Adoption Call for "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01 Thu, 15 August 2019 15:37 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id E37CC12012A for <>; Thu, 15 Aug 2019 08:37:04 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.4
X-Spam-Status: No, score=-1.4 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id MBTxDmpSlwr5 for <>; Thu, 15 Aug 2019 08:37:03 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:4864:20::542]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id BA0DA1200DE for <>; Thu, 15 Aug 2019 08:37:03 -0700 (PDT)
Received: by with SMTP id d1so856975pgp.4 for <>; Thu, 15 Aug 2019 08:37:03 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=sender:from:message-id:mime-version:subject:date:in-reply-to:cc:to :references; bh=ym5HJ33zBxRhs13cRaCeBINUrgJ0Aiedvqxum+EsSxU=; b=FKwuPnWA62inlJzSb8iA7LCTZC86A4cegvqQLogYDgRo+H3oTBz1yX8inACEUFBxNB PIUQkXgViwkm4rLnqV70uD0SWvaSSSyFm3NvPEI/vBlyF5zhnR6JlFEsBx6wBw4xl5q9 OIMpRNspmqPr9GgY7oIFkX04j1DHiih9NagZX3UB8C8634Kd2/Ekl5vFAiQnCytUQBMh QhSZQvovEaQue4JWYn2PxpZu19HVYMciemUlSJZG+H4IofNP1U8VpEI0qKzm5M2iW/R2 ElNO3yF1JtPwE9PD0TiLQfM8kNqLpj1NG0ujdQ1h6kF5E1Bah05ImMIPuWeA7YDwAC8/ +Sow==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:sender:from:message-id:mime-version:subject:date :in-reply-to:cc:to:references; bh=ym5HJ33zBxRhs13cRaCeBINUrgJ0Aiedvqxum+EsSxU=; b=lscK8ItBJK2jZtdO3LWx3librJO8izURpqPRnXiiX1gGQ7mcItVz4kKnQguMEtPr31 dzoX2abWuk5eEn+Pzzs7nWLxSu33ZxFHpTTmHPUk/VDkIqDSgArOoMNf4el7Lt1G2vvL 1n5b/umVdCBfPdh5x+gNDi6LLU3+xxqDLA3lHo86uwlTm89OcEVEv2qZSBRz0L0Vfk/e dqOA8nTrU6KVcP2wkLL0sojwp+uDBkaOvKLScWuPb4WNkraPvxnUd0JwN50uoaSsRBpJ JNZdVzCqkTICQ0zx0eKYLzpgdrvlhvajH04y+eNj33WUa02qQPtZNeP1BEKsBPdwyhuB 8hTw==
X-Gm-Message-State: APjAAAWghxjaKxoi8KsfkGbFT8f7ixZDD3m42CG7tDbtIlVy3EtqFxYS RfGccz3zNYkNB7EpoSNORTs=
X-Google-Smtp-Source: APXvYqzOeFC/0xoCtdzOWptRjh8HfmddFUVkqIl07ngoTgZw4sIP+s9oMCK6evE59hLvHo97hM0MHg==
X-Received: by 2002:a65:6448:: with SMTP id s8mr3966735pgv.223.1565883423030; Thu, 15 Aug 2019 08:37:03 -0700 (PDT)
Received: from [] ([]) by with ESMTPSA id u18sm3181039pfl.29.2019. (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Aug 2019 08:37:02 -0700 (PDT)
Sender: Tony Li <>
Message-Id: <>
Content-Type: multipart/alternative; boundary="Apple-Mail=_2D40C64F-09CB-493C-B40E-61A8378B4377"
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\))
Date: Thu, 15 Aug 2019 08:37:00 -0700
In-Reply-To: <>
Cc: Aijun Wang <>,
To: Robert Raszuk <>
References: <> <01a501d55338$945c2b40$bd1481c0$> <> <>
X-Mailer: Apple Mail (2.3445.104.11)
Archived-At: <>
Subject: Re: [Lsr] LSR Working Group Adoption Call for "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Link State Routing Working Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 15 Aug 2019 15:37:05 -0000

Hi Robert,

> > The hierarchical arrangement of the control plane does NOT imply that the data plane is necessarily hierarchical.  
> Since Aijun posted his question I was trying to think of such model, but failed. 
> While it is easy to envision this with DV protocols say BGP - do you have any pointer to a link state protocol architecture where data plane is non hierarchical (links do not belong to upper levels) while control plane used traverses multiple levels ? 

Consider any topology where two peer areas intersect.  At the intersection, traffic can transition between the areas without entering the parent level.

While I’m at it, I should also point out that the existence of hierarchy for the control plane does not mandate its use. This is another tool in the toolbox. Use the right tool for the job at hand.